Electronic devices such as liquid crystal display devices and semiconductor devices are generally manufactured by forming numerous layers of patterns on a substrate. Photolithography processes have been normally used so far in order to form such patterns. However, photolithography processes have problems in that the manufacturing process is complicated since a prescribed pattern mask needs to be prepared, and chemical etching and a stripping process need to be repeated, and chemical wastes harmful to the environment are produced in large quantities. This soon leads to an increase in the manufacturing costs and discourages product competitiveness. As a new pattern forming method for solving disadvantages of such a photolithography process, a roll printing method using a printing roll has been proposed.
A roll printing method may include various methods, but may be largely classified into a gravure printing method and a reverse offset printing method.
Gravure printing is a printing method in which an ink is coated on a blanket using a transfer roll provided with a blanket formed with patterns, and then printing is carried out after scraping off the excess ink, and is known to be suitable for printing in various fields such as publishing, packing, cellophane, vinyl and polyethylene. Researches for using the gravure printing in manufacturing active devices or circuit patterns used in display devices have been carried out. The gravure printing transfers an ink on a substrate using a transfer roll, therefore, by using a transfer roll corresponding to a target area of a display device, patterns may be formed with one transfer even in a large area display device. Such gravure printing may not only form an ink pattern, which is for resists, on a substrate, but also be used for patterning various patterns of display devices, for example, in liquid crystal display devices, a TFT and a gate line and a data line connected to the TFT as well, pixel electrodes, and metal patterns for a capacitor.
However, a blanket commonly used in gravure printing has been prepared by casting a silicone-based resin in a hard master mold, and the blanket manufactured as above not only has a limit in being manufactured to have a uniform thickness, but also has a difficulty in mass production in a pilot scale. Accordingly, a reverse offset printing method is normally employed in order to form precise micropatterns.
A reverse offset printing method is highly favored in pattern formation in terms that costs are reduced and production rates are enhanced, however, a high-quality blanket is required in order to obtain precise patterns. In other words, the manufacture of a high-quality blanket for printing is a very important technological challenge in that the quality of a pattern is influenced by the property of a blanket.